Risk Factors for Horse Fatality in Thoroughbred Jumps Racing in New Zealand.

The aim of this study was to examine the race-, horse- and jockey-level risk factors for race day fatality in New Zealand Thoroughbred jumps racing using retrospective race day data from the 2011/12 to 2021/22 seasons (n = 8,970 starts). There were 51 race day fatalities resulting in an incidence rate of 5.7 per 1,000 starts (95% C.I. 4.3-7.5). The majority of fatalities were the result of fractures (44/51, 4.9 per 1,000 starts, 95% C.I. 3.7-6.6). Steeplechase and hurdle races had the same incidence of fatal fractures of 4.9 per 1,000 starts (95% C.I. 3.7-6.6, P > .05). Most (70.5%) of the fatal fractures were due to a horse falling during the race. In steeplechase races, horses running in races over 4,201 m were 5.0 times (95% C.I. 1.2-33.0) more likely to sustain a fatal fracture than horses in racing over shorter distances. In hurdle races, horses racing during spring were 2.2 times (95% C.I. 1.0-4.8) more likely to sustain a fatal fracture compared to winter. Due to the low number of suspected cardiac failures and fatal soft tissue injuries, risk factors for these fatalities could not be identified. These data provide a baseline to enable evidence-based regulatory changes and prospectively monitor the effectiveness of changes made.

Dietary Transitions Toward Sustainable Horse Feeding.

Sustainability is the balancing act of optimizing the use of current resources without compromising the current or future environment. Within the agriculture sector the primary focus of sustainability has been to reduce environmental pollution, specifically greenhouse gasses (GHG) emissions, nitrogen emissions, and leaching. For the equine industry the first step towards sustainability is the documentation and critique of current feeding and management practices to permit modifications to enable the industry meet social and legislative obligations. As a monogastric hindgut fermenter on a per kg bodyweight basis the horse has relatively lower GHG emissions compared to ruminants. However, there are several opportunities to further reduce the environmental impact of the equine industry. The majority of these relate to subtle changes, or consideration of, improving feed conversion, using alternative ingredients, and management of fecal material associated with intensive husbandry. To initiate the journey towards sustainability this review documents opportunities with current equine feeding and management practices to reduce the environmental impacts of the equine industry.

The Reporting of Racehorse Fatalities in New Zealand Thoroughbred Flat Racing in the 2011/12-2021/22 Seasons.

Race day fatalities as a consequence of catastrophic musculoskeletal injury and cardiac failure are both a welfare concern and provide a challenge for the social perceptions of equine welfare within the racing industry. To reduce race day fatalities, the risk factors under New Zealand racing conditions need to be identified. The aim of this study was to examine race and horse-level risk factors for fatalities in New Zealand Thoroughbred flat racing using retrospective race day data from the 2011/12-2021/22 racing seasons. Horse and race-level factors associated with a suspected cardiac failure and fatal fracture were identified by merging fatality data with the master race dataset for the corresponding seasons. Most fatalities were associated with fatal fracture (0.4 per 1000 starts, 95% CI 0.4-0.5). Horses which raced over distances > 1600 m were 1.7 times (95% CI 1.2-2.5) more likely to sustain a fatal fracture than horses racing ≤ 1600 m. Male horses and firmer track conditions were also associated with an increase in the risk of fatal fracture. Horses aged 5 years and older were 2.1 (95% CI 1.1-4.6) times more likely to suffer a suspected cardiac failure than younger horses. Changes in the industry reporting system improved the level of detail provided for fatalities, enabling the identification of specific risk factors.

A Bioeconomic Model for the Thoroughbred Racing Industry-Optimisation of the Production Cycle with a Horse Centric Welfare Perspective.

The Thoroughbred racing industry faces new and competing pressures to operate within a modern, changing society. Three major moderators drive the focus and productivity of the industry worldwide: economic sustainability, horse biology and social licence to operate. This review proposes that despite the apparent homogeneity in the structure of racing across jurisdictions due to international regulation of the sport, there are significant differences within each jurisdiction in each of the three moderators. This creates challenges for the comparison of injury risk factors for racehorses within the industry across different jurisdictions. Comparison of the relative distribution of racing and gambling metrics internationally indicates that the Asian jurisdictions have a high focus on gambling efficiency and high economic return of the product, with a high number of starts per horse and the highest relative betting turnover. In contrast, the racing metrics from the USA have proportionally low racing stakes and fewer horses per race. These differences provide insight into the sociology of horse ownership, with a shift from the long-term return on investment held by most jurisdictions to a short-term transitional view and immediate return on investment in others. Wastage studies identify varying risks influenced by the predominant racing culture, training methods, production focus and environment within individual jurisdictions. Increasing societal pressure to maintain high racehorse welfare and reduce the negative impact of gambling poses fluctuating risks to each jurisdiction's social licence to operate. Based on the data presented within this review, the authors propose that the use of a bioeconomic model would permit consideration of all three moderators on industry practice and optimisation of the jurisdiction-specific production cycle with a horse-centric welfare perspective.

Physiological Demands and Muscle Activity of "Track-Work" Riding in Apprentice Jockeys.

PURPOSE: To enhance performance in race riding, knowledge of current training workload is required. The objectives of this study were to quantify the physiological demands and profile the muscle activity of jockeys riding track-work. METHODS: Ten apprentice jockeys and 48 horses were instrumented with heart-rate monitors, accelerometers, and a surface electromyography BodySuit (recording 8 muscle groups: quadriceps, hamstrings, gluteal, lower back, obliques, abdominal, trapezial, and pectoral) that recorded continuously while riding their normal morning track-work. Data were extracted and time matched into 200-m sections for analysis once the jockey reached steady-state canter (6.9 m·s-1). RESULTS: Jockeys rode a mean (±SD) of 6 (1) horses each morning over 2.5 hours, spending ∼30 minutes at a canter (8.8 [ 0.7] m·s-1), with mean heart rate of 129 (11) beats·min-1 and ratings of perceived exertion representing easy-/moderate-intensity exercise. Mean magnitude of horse (0.17 [0.01] m) and jockey center of mass (0.16 [0.02] m) displacement per stride differed from that of the jockey's head (0.11 [0.01] m, P < .05). The majority of horse oscillation was damped in the upper body with a 3-fold reduction in the medio/lateral and fore/aft planes (P < .05), to minimize jockey head movement. Lower-body muscles absorbed horse motion, with core and upper-body muscles important for postural stabilization. CONCLUSIONS: The physiological demands of riding track-work were low, with no evidence of fatigue. Future research on jockeys in races as comparison would identify the specific requirements of a jockey-specific physical conditioning program.

Race-Level Reporting of Incidents Using an Online System during Three Seasons (2019/2020-2021/2022) of Thoroughbred Flat Racing in New Zealand.

In the 2019/20 Thoroughbred racing season, the paper-based reporting process of stipendiary steward reports was upgraded to an online system ('Infohorse database') to allow for the rapid entry of precise event and injury data. The objectives of this study were to describe the incident and non-incident examinations during the 2019/20, 2020/21, and 2021/22 Thoroughbred flat racing seasons in New Zealand and describe the primary injury and reporting outcomes. The introduction of the online system was associated with fewer miscoding events with horse identification (0.1%). An improvement in the definition and prompts in reporting within the online system compared with the previous paper-based system resulted in a greater frequency of non-incident examinations being undertaken. The increased frequency of reporting the clinical outcome, 'no observable abnormalities detected' (NOAD), demonstrates the role of stipendiary stewards to carry out routine screening. The frequency of most clinical findings, such as musculoskeletal fractures (0.5 per 1000 starts, 95% CI = 0.3-0.6), remained similar compared to previously reported data using the paper-based system. The online system provided a more structured dataset compared with the paper-based system, making it a useful tool for the monitoring of incidents, injuries, and potential risk factors within Thoroughbred racing in New Zealand. Therefore, evidence-based changes to the management and structure of racing can be undertaken to ensure the industry meets its duty of care for racehorse and jockey welfare.

Undetectable vitamin D3 in equine skin irradiated with ultraviolet light.

Vitamin D requirements for most animals are expected to be fulfilled through daily exposure of the skin to solar ultraviolet B radiation. The synthesis of vitamin D3 in skin depends on different factors including melanin pigmentation, the amount of UVB radiation reaching the skin, type of clothing/hair coat, latitude and altitude, season, and time of day. Alternatively vitamin D2 may be obtained from UVB irradiated pasture species. Recent studies have shown that in unsupplemented grazing horses 25-hydroxyvitamin D2 is the predominant form of vitamin D in plasma, and that 25OHD3 is undetectable suggesting horses may rely on diet to obtain vitamin D. In order to mimic the natural environment of skin to sunlight exposure, five equine and two ovine devitalized skin samples were irradiated with 5 J/cm2 of UVB light followed by measurement of 7-dehydrocholesterol (7-DHC) and vitamin D3 concentrations using reverse-phase high pressure liquid chromatography (HPLC). HPLC revealed the presence of 7-DHC in the skin of both horses and sheep. Vitamin D3 was undetectable in both ovine and equine skin prior to irradiation, but after irradiation with UVB light, ovine skin showed an increase in vitamin D3 concentration (mean 0.16 ± 0.07 µg/g), whereas vitamin D3 was undetectable in equine skin. These results provide additional evidence that horses make negligible quantities of vitamin D3 in their skin after exposure to UVB light and may therefore rely on their diet as a primary source of vitamin D.

Race-Level Reporting of Incidents Using the New Online System During Two Seasons (2019/2020-2020/2021) of Harness Racing in New Zealand.

After establishing a baseline of stipendiary stewards' reporting using the paper-based system in the 2015/16 and 2016/17 seasons of harness racing, it is important to examine if the implementation of an online system has altered frequency and descriptors used for clinical outcomes. The objective of this study was to describe the race level injury and reporting outcomes, and horse- and race-level variables associated with the rate of the reporting of these outcomes during the 2019/20 and2020/21 harness racing seasons in New Zealand. The introduction of the online system was associated with few (0.01%) miscoding events associated with horse identification. There was a shift in the frequency of reporting non-incident examinations, possibly due to better definition and prompts within the online system. The coding category, no observable abnormalities detected (NOAD) had the greatest number of entries, reflecting that the majority of examinations were associated with general screening rather than adverse events occurring during warm-up or the race. The frequency of recordings for most clinical findings was consistent between the old paper-based system and the new online system. The incidence of musculoskeletal fractures remained low (0.12 per 1,000 starts, 95%CI = 0.05-0.28). The online system has the potential to provide a useful tool to prospectively monitor the reporting of injuries and conditions associated with harness racing in New Zealand.

Race-Level Reporting of Incidents during Two Seasons (2015/16 to 2016/17) of Thoroughbred Flat Racing in New Zealand.

The objective of this study was to describe the incident and non-incident reports of Thoroughbred flat racing in New Zealand. Retrospective stipendiary stewards' reports of race day events during the 2015/2016 and 2016/2017 racing season were examined. The primary injury and reporting outcomes were analysed to assess the horse- and race-level risk factors associated with the occurrence of incident and non-incident reports. The number of incident and non-incident events and binomial exact 95% confidence intervals were calculated per 1000 horse starts. Most reports were for non-incidents and examinations were requested for poor performance (10.3 per 1000 races, 95% CI = 9.5-11.1). Horses running in open-class races had greater odds of having an incident than horses in lower-rating classes. The incidence of musculoskeletal injuries (1.3 per 1000 races, 95% CI = 1.13-1.40) and fractures (0.6 per 1000 races, 95% CI = 0.39-0.74) were low and similar to previous New Zealand reports. There was a low incidence of epistaxis (0.8 per 1000 races, 95% CI = 0.69-0.92) possibly due to trainers screening susceptible horses before entering them in races, due to the regulatory consequences of an episode of epistaxis during a race.

Race-Level Reporting of Incidents during Two Seasons (2015/16 to 2016/17) of Harness Racing in New Zealand.

The objective of this study was to describe the incident and non-incident reporting of harness racing in New Zealand, the primary injury and reporting outcomes, and to examine horse- and race-level variables associated with the odds of these outcomes. Retrospective stipendiary stewards' reports of race day events during the 2015/16 to 2016/17 racing seasons were examined. The number of incident and non-incident events and binomial exact 95% confidence intervals (CI) were calculated per 1000 horse starts. Most reports were for non-incidents and an examination was requested for poor performance (11.06 per 1000 starts (95% CI = 10.23-11.89). Races with more than eight participants were 1.9 (95% CI = 1.13-3.4) times more likely to have an incident than races with eight or less participants. The low incidence of significant injuries such as fractures (0.13 per 1000 starts (95% CI = 0.03-0.23) reflects the lower risk of injury in harness racing compared to Thoroughbred racing. The high incidence of poor performance reports highlights the steward's role in maintaining animal welfare to a high standard.

Growth and Bone Development in the Horse: When Is a Horse Skeletally Mature?

Within the lay literature, and social media in particular, there is often debate about the age at which a horse should be started and introduced to racing or sport. To optimize the welfare and longevity of horses in racing and sport, it is important to match exercise with musculoskeletal development and the ability of the musculoskeletal system to respond to loading. The justification for not exercising horses at a certain age is often in contrast to the scientific literature and framed, with incorrect generalizations, with human growth. This review provides a relative comparison of the growth and development of the horse to the descriptors used to define growth and development in humans. Measures of physeal closure and somatic growth demonstrate that the horse completes the equivalent of rapid infant growth by weaning (4-6 months old). At approximately 11 months old, the horse completes the equivalent of the childhood phase of growth and enters puberty. At 2 years old, the horse has achieved most measures of maturity used within the human literature, including the plateauing of vertical height, closure of growth plates, and adult ratios of back length:wither height and limb length:wither height. These data support the hypothesis that the horse evolved to be a precocious cursorial grazer and is capable of athletic activity, and use in sport, relatively early in life.

Immune response to allogeneic equine mesenchymal stromal cells.

BACKGROUND: Mesenchymal stromal cells (MSCs) are believed to be hypoimmunogeneic with potential use for allogeneic administration. METHODS: Bone marrow was harvested from Connemara (n = 1), Standardbred (n = 6), and Thoroughbred (n = 3) horses. MSCs were grouped by their level of expression of major histocompatibility factor II (MHC II). MSCs were then sub-grouped by those MSCs derived from universal blood donor horses. MSCs were isolated and cultured using media containing fetal bovine serum until adequate numbers were acquired. The MSCs were cultured in xenogen-free media for 48 h prior to use and during all assays. Autologous and allogeneic MSCs were then directly co-cultured with responder leukocytes from the Connemara horse in varying concentrations of MSCs to leukocytes (1:1, 1:10, and 1:100). MSCs were also cultured with complement present and heat-inactivated complement to determine whether complement alone would decrease MSC viability. MSCs underwent haplotyping of their equine leukocyte antigen (ELA) to determine whether the MHC factors were matched or mismatched between the donor MSCs and the responder leukocytes. RESULTS: All allogeneic MSCs were found to be ELA mismatched with the responder leukocytes. MHC II-low and universal blood donor MSCs caused no peripheral blood mononuclear cell (PBMC) proliferation, no increase in B cells, and no activation of CD8 lymphocytes. Universal blood donor MSCs stimulated a significant increase in the number of T regulatory cells. Neutrophil interaction with MSCs showed that universal blood donor and MHC II-high allogeneic MSCs at the 6 h time point in co-culture caused greater neutrophil activation than the other co-culture groups. Complement-mediated cytotoxicity did not consistently cause MSC death in cultures with active complement as compared to those with inactivated complement. Gene expression assays revealed that the universal blood donor group and the MHC II-low MSCs were more metabolically active both in the anabolic and catabolic gene categories when cultured with allogeneic lymphocytes as compared to the other co-cultures. These upregulated genes included CD59, FGF-2, HGF, IDO, IL-10, IL-RA, IL-2, SOX2, TGF-ß1, ADAMSTS-4, ADAMSTS-5, CCL2, CXCLB/IL-8, IFNγ, IL-1ß, and TNFα. CONCLUSIONS: MHC II-low MSCs are the most appropriate type of allogeneic MSC to prevent activation of the innate and cell-mediated component of the adaptive immune systems and have increased gene expression as compared to other allogeneic MSCs.

Preliminary Examination of the Biological and Industry Constraints on the Structure and Pattern of Thoroughbred Racing in New Zealand over Thirteen Seasons: 2005/06-2017/18.

This study aimed to examine thirteen seasons of flat racing starts (n = 388,964) in the context of an ecological system and identify metrics that describe the inherent characteristics and constraints of the New Zealand Thoroughbred racing industry. During the thirteen years examined, there was a 2-3% per year reduction in the number of races, starts and number of horses. There was a significant shift in the racing population with a greater number of fillies (aged 2-4 years) having a race start, and subsequent longer racing careers due to the inclusion of one more racing preparation post 2008 (p < 0.05). Additionally, there was an increasingly ageing population of racehorses. These changes resulted in more race starts in a career, but possibly because of biological constraints, there was no change in the number of race starts per season, starts per preparation, or days spelling between preparations (p < 0.05). There was no change in the proportion of horses having just one race start (14% of new entrants), indicating that the screening for suitability for a racing career remained consistent. These data identify key industry parameters which provide a basis for future modelling of intervention strategies to improve economic performance and reduce horse injury. Consideration of the racing industry as a bio-economic or ecological model provides framework to test how the industry may respond to intervention strategies and signal where changes in system dynamics may alter existing risk factors for injury.

Resilience of Faecal Microbiota in Stabled Thoroughbred Horses Following Abrupt Dietary Transition between Freshly Cut Pasture and Three Forage-Based Diets.

The management of competition horses in New Zealand often involves rotations of short periods of stall confinement and concentrate feeding, with periods of time at pasture. Under these systems, horses may undergo abrupt dietary changes, with the incorporation of grains or concentrate feeds to the diet to meet performance needs, or sudden changes in the type of forage fed in response to a lack of fresh or conserved forage. Abrupt changes in dietary management are a risk factor for gastrointestinal (GI) disturbances, potentially due to the negative effects observed on the population of GI microbiota. In the present study, the faecal microbiota of horses was investigated to determine how quickly the bacterial communities; (1) responded to dietary change, and (2) stabilised following abrupt dietary transition. Six Thoroughbred mares were stabled for six weeks, consuming freshly cut pasture (weeks 1, 3 and 5), before being abruptly transitioned to conserved forage-based diets, both offered ad libitum. Intestinal markers were administered to measure digesta transit time immediately before each diet change. The conserved forage-based diets were fed according to a 3 × 3 Latin square design (weeks 2, 4 and 6), and comprised a chopped ensiled forage fed exclusively (Diet FE) or with whole oats (Diet FE + O), and perennial ryegrass hay fed with whole oats (Diet H + O). Faecal samples were collected at regular intervals from each horse following the diet changes. High throughput 16S rRNA gene sequencing was used to evaluate the faecal microbiota. There were significant differences in alpha diversity across diets (p < 0.001), and a significant effect of diet on the beta diversity (ANOSIM, p = 0.001), with clustering of samples observed by diet group. There were differences in the bacterial phyla across diets (p < 0.003), with the highest relative abundances observed for Firmicutes (62-64%) in the two diets containing chopped ensiled forage, Bacteroidetes (32-38%) in the pasture diets, and Spirochaetes (17%) in the diet containing hay. Major changes in relative abundances of faecal bacteria appeared to correspond with the cumulative percentage of intestinal markers retrieved in the faeces as the increasing amounts of digesta from each new diet transited the animals. A stable faecal microbiota profile was observed in the samples from 96 h after abrupt transition to the treatment diets containing ensiled chopped forage. The present study confirmed that the diversity and community structure of the faecal bacteria in horses is diet-specific and resilient following dietary transition and emphasised the need to have modern horse feeding management that reflects the ecological niche, particularly by incorporating large proportions of forage into equine diets.

Seasonal Variation in the Faecal Microbiota of Mature Adult Horses Maintained on Pasture in New Zealand.

Seasonal variation in the faecal microbiota of forage-fed horses was investigated over a 12-month period to determine whether the bacterial diversity fluctuated over time. Horses (n = 10) were maintained on pasture for one year, with hay supplemented from June to October. At monthly intervals, data were recorded on pasture availability and climate (collected continuously and averaged on monthly basis), pasture and hay samples were collected for nutrient analysis, and faecal samples were collected from all horses to investigate the diversity of faecal microbiota using next-generation sequencing on the Illumina MiSeq platform. The alpha diversity of bacterial genera was high in all samples (n = 118), with significantly higher Simpson's (p < 0.001) and Shannon-Wiener (p < 0.001) diversity indices observed during the months when horses were kept exclusively on pasture compared to the months when pasture was supplemented with hay. There were significant effects of diet, season, and month (ANOSIM, p < 0.01 for each comparison) on the beta diversity of bacterial genera identified in the faeces. While there was some inter-horse variation, hierarchical clustering of beta diversity indices showed separate clades originating for samples obtained during May, June, and July (late-autumn to winter period), and January, February, and March (a period of drought), with a strong association between bacterial taxa and specific nutrients (dry matter, protein, and structural carbohydrates) and climate variables (rainfall and temperature). Our study supports the hypothesis that the diversity and community structure of the faecal microbiota of horses kept on pasture varied over a 12-month period, and this variation reflects changes in the nutrient composition of the pasture, which in turn is influenced by climatic conditions. The findings of this study may have implications for grazing management and the preparation of conserved forages for those horses susceptible to perturbations of the hindgut microbiota.

Monitoring equine ascarid and cyathostomin parasites: Evaluating health parameters under different treatment regimens.

BACKGROUND: Strongylid and ascarid parasites are omnipresent in equine stud farms, and ever-increasing levels of anthelmintic resistance are challenging the industry with finding more sustainable and yet effective parasite control programs. OBJECTIVES: To evaluate egg count levels, bodyweight and equine health under defined parasite control protocols in foals and mares at two Standardbred and two Thoroughbred stud farms. STUDY DESIGN: Longitudinal randomised field trial. METHODS: A total of 93 foals were enrolled and split into two treatment groups, and 99 mares were enrolled and assigned to three treatment groups. All horses underwent a health examination, and episodes of colic or diarrhoea were recorded at each faecal collection date. Bodyweights were assessed using a weight tape, and mares were body condition scored. Group A foals (FA) were dewormed at 2 and 5 months of age with a fenbendazole/ivermectin/praziquantel product, while group B foals (FB) were dewormed on a monthly basis, alternating between the above-mentioned product and an oxfendazole/pyrantel embonate product. Group A mares (MA) were dewormed twice with fenbendazole/ivermectin/praziquantel, group B mares (MB) were dewormed with the same product, when egg counts exceeded 300 strongylid eggs per gram, and group C mares (MC) were dewormed every 2 months, alternating between the two products. Health data were collected monthly for 6 months (foals) and bimonthly for 13 months (mares). Data were analysed with mixed linear models and interpreted at the α = 0.05 significance level. RESULTS: There were no significant bodyweight differences between foal groups, but MA mares were significantly lighter than the other two groups. Very few health incidents were recorded. Foals in group FA had significantly higher ascarid and strongylid egg counts, whereas no significant differences were observed between mare groups. MAIN LIMITATIONS: Study duration limited to one season. CONCLUSIONS: Anthelmintic treatment intensity was lowered from the traditional intensive regimes without measurable negative health consequences for mares and foals.

Seroprevalence of Leptospira in Racehorses and Broodmares in New Zealand.

A cross-sectional survey was conducted to determine the seroprevalence of Leptospira in a cohort of horses and to evaluate potential risk factors for Leptospira seropositivity in horses in New Zealand. The convenience sample included 499 Thoroughbred racing and breeding horses from 25 commercial properties in North Island, New Zealand. A questionnaire was used to collect demographic data on horses and property-level information on grazing and management practices, pest (rodent) management, access to natural waterways, other livestock on the property, and possible contact with wildlife. The microscopic agglutination test was used to test sera for serovars Ballum, Copenhageni, Hardjo (bovis), Pomona, and Tarassovi. Logistic regression was used to investigate the risk factors for Leptospira seropositivity to at least one serovar and for each serovar individually. A total of 124 (25%, 95% confidence interval (CI) 21-29%) horses had positive titres to any one of the five serovars. The seroprevalence of Ballum, Copenhageni, Hardjo (bovis), Pomona, and Tarassovi was 5% (95% CI 3-7%), 9% (95% CI 7-12%), 6% (95% CI 4-8%), 6% (95% CI 4-8%), and 6% (95% CI 4-8%), respectively. Broodmares, compared to racehorses and alternately grazing horses with sheep, increased the odds of exposure to any one serovar, whilst grazing the same time as sheep and alternately grazing horses with cattle increased the odds of exposure to Ballum and Hardjo (bovis), respectively. Historical exposure to Leptospira in racing and breeding horses was identified, and risk factors were consistent with pasture-based exposure.

Horses Used for Educational Purposes in New Zealand: A Descriptive Analysis of Their Use for Teaching.

Horses are used in practical teaching classes in many equine and veterinary science degree programmes to develop and refine the handling and clinical skills of students. In this study, the activities of 24 teaching horses grouped in three herds were investigated over an entire calendar year. Although also used for research and general husbandry, teaching-related activities were the predominant use of the horses. Herd B was used for a greater number of teaching sessions (median = 28, IQR = 27-29.5 per year) than herds M (median = 21, IQR = 20-21 per year) and T (median = 19.5, IQR = 13.75-25.5 per year), which translates to a relatively low workload (one or two weekly sessions during the teaching semester). Sedation was used in dentistry classes (in alignment with national best practice standards) but was rarely required for other teaching activities. Mare reproductive rectal- and medical rectal examination practical classes (specific to 5th-year veterinary teaching and characterised by more restraint (in stocks)) were significantly shorter and had fewer students per horse than the other practical classes. Although the low workload reported suggests an opportunity to increase students' exposure to horses without compromising the horses' welfare, further investigation to determine specific stressors to the horses in the teaching environment may be required.

Incidence and risk factors for race-day jockey falls over fourteen years.

OBJECTIVES: To determine the incidence of, and risk factors for, race-day jockey falls occurring in Thoroughbred flat and jumps (hurdle and steeplechase) racing. DESIGN: Retrospective cohort study. METHODS: Incidence rates for race-day jockey falls over 14 racing seasons in New Zealand (n=421,596 race-day starts) were calculated per 1000 rides. Univariable and multivariable analyses of jockey, horse and race level risk factors were conducted with Poisson regression in a generalized linear mixed model. RESULTS: Most races (97%, n=407,948 race starts) were flat racing with 10 races/race-day, whilst most jumps races were longer and had 2 races/race-day. The rate of jockey falls was higher in steeplechase racing (99.9/1000, 95% CI 92.2-108.4) than hurdle (53.2/1000, 95% CI 48.7-58.3) and flat racing (1.2/1000, 95% CI 1.1-1.3, p<0.001). Experienced athletes (both horse and jockey) had lower IRR. In flat racing, IRR increased linearly with the number of race-day rides by the jockey. In jumps races, IRR increased with a fall in a previous race (IRR 1.5/1000, 95% CI 1.3-1.7, p<0.001). A shorter jumps race distance reduced the IRR of a jockey fall. CONCLUSIONS: Athlete experience was associated with risk of jockey falls. The linearity of race ride number with IRR and longer distance in jumps racing, indicated that cognitive or physiological fatigue may play a role in the risk of a race-day fall. This data highlights the role sport-specific conditioning programmes may have on reducing risk.

CellTrace Violet™ inhibits equine lymphocyte proliferation.

CellTrace Violet™ is a commonly used fluorescent dye used with flow cytometry to identify cell proliferation. Activated equine lymphocytes were examined using flow cytometry, microscopy and tritiated thymidine proliferation assays. CellTrace Violet™ was incorporated into the equine lymphocytes effectively. Equine lymphocytes proliferated when activated with pokeweed mitogen, but did not proliferate when previously stained with CellTrace Violet™. Serial dilutions of CellTrace Violet™ did not eliminate the inhibition of activated lymphocytes. Equine lymphocyte viability was greater than 90 % for both stained and unstained cells. Based on these data, CellTrace Violet™ is not recommended for the assessment of lymphocyte proliferation in equine cells. The mechanism of inhibition of equine lymphocyte proliferation by CellTrace Violet™ is unknown.